Nadrazi Ruzyne, in spite of sharing a name with the nearby airport, is nevertheless not the best way to get to the airport. In that case, you would be better off getting the Metro to the north end of the A Line at Dejvicka, and then getting either bus #119, or bus #AE, which is more expensive, but an express. Nadrazi Ruzyne actually serves the Prague suburb of Ruzyne, and is still very steam-era-looking, complete with upper-quadrant semaphore signals. It still has its interlocking boxes, too, although I don't know if they're actually what's controlling the signals.